Information About
the Cisco Nexus 2000 Series Fabric Extender

The
Cisco Nexus 2000 Series
Fabric Extender,
also known as FEX, is a highly scalable and flexible server networking solution
that works with
Cisco Nexus Series
devices to provide high-density, low-cost connectivity for server aggregation.
Scaling across 1-Gigabit Ethernet, 10-Gigabit Ethernet, unified fabric, rack,
and blade server environments, the
Fabric Extender
is designed to simplify data center architecture and operations.

The
Fabric Extender
integrates with its parent switch, which is a
Cisco Nexus Series
device, to allow automatic provisioning and configuration taken from the
settings on the parent device. This integration allows large numbers of servers
and hosts to be supported by using the same feature set as the parent device, including security and
quality-of-service (QoS) configuration parameters,
with a single management domain. The
Fabric Extender
and its parent switch enable a large multipath, loop-free, active-active data
center topology without the use of the Spanning Tree Protocol (STP).

Figure 1. Single
Management Domain

The
Cisco Nexus 2000 Series
Fabric Extender
forwards all traffic to its parent
Cisco Nexus Series
device over 10-Gigabit Ethernet fabric uplinks, which allows all traffic to be
inspected by policies established on the
Cisco Nexus Series
device.

No software is
included with the
Fabric Extender.
The software is automatically downloaded and upgraded from its parent device.

Fabric Extender
Terminology

Some terms used in
this document are as follows:

Fabric
interface—A 10-Gigabit Ethernet uplink port that is designated for connection
from the
Fabric Extender
to its parent switch. A fabric interface cannot be used for any other purpose.
It must be directly connected to the parent switch.

Note

A fabric
interface includes the corresponding interface on the parent switch. This
interface is enabled when you enter the
switchport mode
fex-fabric command.

Port channel
fabric interface—A port channel uplink connection from the
Fabric Extender
to its parent switch. This connection consists of fabric interfaces that are
bundled into a single logical channel.

Host
interface—An Ethernet host interface for connection to a server or host system.

Note

Do not connect
a bridge or switch to a host interface. These interfaces are designed to
provide end host or server connectivity.

Note

On Cisco Nexus 2348TQ and Nexus 2348UPQ FEX, if a port channel
is used to connect a parent switch with a
Fabric Extender
device, the port channels can have maximum of 8 ports.

The Nexus 2348 FEX devices have a total of 6 * 40 Gigabit
Ethernet uplink ports towards the parent switch. If these are used with native
40G uplinks port on a parent switch, then there is no limitation. All 6 ports
can be used in either single homed or dual homed configuration. You can also
use 40 Gigabit Ethernet uplink ports on the N2348
Fabric Extender
device with 10 Gigabit Ethernet ports on the parent switch when used with the
appropriate cabling. A maximum of 8 ports can be added to the port channel
between the parent switch and
Fabric Extender
device. If it is a dual homed setup, VPC to the
Fabric Extender
device, only 4 ports per switch are allowed in the port channel.

Fabric Extender Features

The
Cisco Nexus 2000 Series Fabric Extender allows a single switch—and a
single consistent set of switch features—to be supported across a large number
of hosts and servers. By supporting a large server-domain under a single
management entity, policies can be enforced more efficiently.

Some of the features of the parent switch cannot be extended onto the
Fabric Extender.

Layer 2 Host
Interfaces

All
Fabric Extender
host interfaces run as spanning tree edge ports with BPDU Guard enabled and you
cannot configure them as spanning tree network ports.

You can
connect servers that use active/standby teaming, 802.3ad port channels, or
other host-based link redundancy mechanisms to
Fabric Extender
host interfaces.

Any device
that is running spanning tree connected to a
Fabric Extender
host interface results in that host interface being placed in an error-disabled
state when a BPDU is received.

You can
connect only virtual switches that leverages a link redundancy mechanism not
dependent on spanning tree such as Cisco FlexLink or vPC (with the BPDU Filter
enabled) to a
Fabric Extender
host interface. Because spanning tree is not used to eliminate loops, you
should ensure a loop-free topology below the
Fabric Extender
host interfaces.

You
can enable host interfaces to accept Cisco Discovery Protocol (CDP) packets.
This protocol only works when it is enabled for both ends of a link.

Note

CDP is not
supported on fabric interfaces when the
Fabric Extender
is configured in a virtual port channel (vPC) topology.

Ingress and
egress packet counters are provided on each host interface.

Host Port
Channel

The following fabric
extenders support port channel host interface configurations. Up to eight
interfaces can be combined in a port channel. The port channel can be
configured with or without Link Aggregation Control Protocol (LACP).

Cisco Nexus 2248TP

Cisco Nexus 2348UPQ

Cisco Nexus 2348TQ

Cisco Nexus 2232PP

Cisco Nexus 2332TQ

Cisco Nexus 2224TP

Cisco Nexus 2248PQ

Cisco Nexus B22 Fabric
Extender for Fujitsu (N2K-B22FTS-P)

Cisco Nexus B22 Fabric
Extender for Dell (N2K-B22DELL-P)

Cisco Nexus B22 Fabric
Extender for HP (N2K-B22HP-P)

Cisco Nexus B22 Fabric
Extender for IBM (N2K-B22IBM-P)

VLANs and Private VLANs

The
Fabric Extender supports Layer 2 VLAN trunks and IEEE 802.1Q VLAN encapsulation. Host interfaces can be members of private VLANs with the following restrictions:

You can configure a host interface as an isolated or community access port only.

You cannot configure a host interface as a promiscuous port.

You cannot configure a host interface as a private VLAN trunk port.

For more information about VLANs, see the chapter in this guide on Configuring VLANs.

Virtual Port Channels

With a virtual port channel (vPC), you can
configure topologies where a
Cisco Nexus Fabric Extender
is connected to a pair of
parent
switches or a pair of
Fabric Extenders are connected to a single parent switch.
The vPC can provide multipath connections, which allow you to create
redundancy between the nodes on your network.

Note

A port channel between two FEXs that are connected to the same Cisco Nexus device is not supported. Virtual port channels (vPCs) cannot span two different FEXs when connected to the same Cisco Nexus device.

The following vPC topologies are possible with
the
Fabric Extender:

The
parent
switches are connected single homed to
Fabric Extenders
that are subsequently connected to servers with dual interfaces (see the following figure).

Figure 2. Single Homed Fabric Extender vPC Topology

The
Fabric Extender
is connected dual homed to two upstream
parent
switches and connected downstream to single homed servers (see the following figure).

Figure 3.
Dual Homed Fabric Extender
vPC Topology

This configuration is also called an Active-Active topology.

Note

Port channels between two Fabric Extenders connected to the same Cisco Nexus device is not supported vPCs cannot span two different Fabric Extenders that are connected to the same physical Cisco Nexus device.

Fibre Channel over Ethernet Support

The Cisco Nexus 2232PP and Cisco Nexus 2248PQ support Fibre Channel over Ethernet (FCoE) with the following restrictions:

Protocol
Offload

To reduce the load
on the control plane of the
Cisco Nexus Series
device,
Cisco NX-OS
allows you to offload link-level protocol processing to the
Fabric Extender
CPU. The following protocols are supported:

Link Layer
Discovery Protocol (LLDP)

Cisco Discovery
Protocol (CDP)

Link Aggregation
Control Protocol (LACP)

Quality of Service

The
Fabric Extender
provides two user queues for its quality-of-service (QoS) support, one for all
no-drop classes and one for all drop classes. The classes configured on its
parent switch are mapped to one of these two queues; traffic for no-drop
classes is mapped to one queue and traffic for all drop classes is mapped to
the other. Egress policies are also restricted to these two classes.

The Cisco Nexus Series device provides two predefined type qos class maps for matching
broadcast or multicast traffic; class-all-flood and class-ip-multicast. These
classes are ignored on the
Fabric Extender.

The
Fabric Extender
uses IEEE 802.1p class of service (CoS) values to associate traffic with the
appropriate class. Per-port quality of service (QoS) configuration and CoS-based egress queuing are
also supported.

Host interfaces support pause frames, which are implemented using IEEE 802.3x
link-level flow control (LLC). By default, flow control send is on and flow
control receive is off on all host interfaces. Autonegotiation is enabled on
the host interfaces. Per-class flow control is set according to the QoS
classes.

Host interfaces support jumbo frames (up to 9216 bytes); however, a
per-host interface maximum transmission unit (MTU) is not supported. Instead,
MTU is set according to the QoS classes. You modify MTU by setting policy and
class maps on the parent switch. Because the
Fabric Extender
has only two user queues, the MTU for the drop-queue is set to the maximum MTU
of all drop classes and the MTU on the no-drop queue is set to the maximum MTU
of all no-drop classes.

For more information about LLC and quality-of-service, see the Quality of Service Configuration Guide for your device.

Access Control Lists

The
Fabric Extender supports the full range of ingress access control lists (ACLs) that are available on its parent Cisco Nexus Series device.

For more information about ACLs, see the Security Configuration Guide for your device.

IGMP
Snooping

IGMP snooping is
supported on all host interfaces of the
Fabric Extender.

The
Fabric Extender and its parent switch support IGMPv3
snooping based only on the destination multicast MAC address. It does not
support snooping that is based on the source MAC address or on proxy reports.

Switched Port
Analyzer

You can configure
the host interfaces on the
Fabric Extender as Switched Port Analyzer
(SPAN) source ports. You cannot configure
Fabric Extender ports as a SPAN destination.
Only one SPAN session is supported for all the host interfaces on the same
Fabric Extender. Ingress source (Rx), egress
source (Tx), or both ingress and egress monitoring are supported.

Note

All IP multicast
traffic on the VLANs that a
Fabric Extender host interface belongs to is
captured in the SPAN session. You cannot separate the traffic by IP multicast
group membership.

If you configure
ingress monitoring and egress monitoring for host interfaces on the same
Fabric Extender, you might see a packet
twice: once as the packet ingresses on an interface with Rx configured, and
again as the packet egresses on an interface with Tx configured.

For
more information about SPAN, see the System Management Configuration Guide for
your device.

Fabric Interface
Features

The
FEX fabric interfaces support static port channels and priority flow control
(PFC). PFC allows you to apply pause functionality to specific classes of
traffic on an interface (instead of all the traffic on the interface).
During the initial discovery and association process, SFP+ validation and
digital optical monitoring (DOM) are performed as follows:

The FEX
performs a local check on the uplink SFP+ transceiver. If it fails the security
check, the LED flashes but the link is still allowed to come up.

The FEX local
check is bypassed if it is running its backup image.

The parent
switch performs SFP validation again when the fabric interface is brought up.
It keeps the fabric interface down if SFP validation fails.

After an interface
on the parent switch is configured in fex-fabric mode, all other features that
were configured on that port and are not relevant to this mode are deactivated.
If the interface is reconfigured to remove fex-fabric mode, the previous
configurations are reactivated.

Note

Per class flow
control mode is enabled by default on the fabric interfaces. When a fabric
interface is configured on the parent switch, PFC mode is enabled by default
and cannot be changed.

Note

For a 2248PQ,
all fabric interfaces need to be bundled into a single fabric port channel.
They cannot be used to connect the parent switch as individual ports.

For
more information about PFC, see the Quality of Service Configuration Guide for
your device.

Oversubscription

In a switching
environment, oversubscription is the practice of connecting multiple devices to
the same interface to optimize port usage. An interface can support a
connection that runs at its maximum speed. Because most interfaces do not run
at their maximum speeds, you can take advantage of unused bandwidth by sharing
ports. Oversubscription, which is a function of the available fabric interfaces
to active host interfaces, provides cost-effective scalability and flexibility
for Ethernet environments.

The
Cisco Nexus 2148TFabric Extender has 4 10-Gigabit Ethernet fabric
interfaces and 48 1000BASE-T (1-Gigabit) Ethernet host interfaces. With this
system, you can have any number of configurations. For example, you can
configure the following:

The
Cisco Nexus 2248TP can be run with no
oversubscription when its host interfaces are running in 100-Mb mode.

The
Cisco Nexus 2248PQ Fabric Extender has 16 10-Gigabit Ethernet fabric interfaces
and 48 10-Gigabit Ethernet host interfaces. All host interfaces use all of the
available fabric interfaces. (Static pinning is not supported. Port-channel
mode is only supported on fabric interfaces.) When all host interfaces are
sending traffic to all fabric interfaces, the maximum oversubscription ratio
for the Cisco Nexus 2248PQ is 3:1.

The
Cisco Nexus 2232PPFabric Extender has 8 10-Gigabit Ethernet fabric
interfaces and 32 10-Gigabit Ethernet host interfaces. All host interfaces use
all of the available fabric interfaces.
When all host interfaces are sending traffic
to all fabric interfaces, the maximum oversubscription ratio for the Cisco
Nexus 2232PP is 4:1.

The
Cisco Nexus 2232TMFabric Extender has 8 10-Gigabit Ethernet fabric
interfaces and 32 10G-BASE-T (10-Gigabit) Ethernet host interfaces. With this
system, you can configure a 4 to 1 oversubscription (4 host interfaces for one
fabric interface) or higher.

The
Cisco Nexus 2224TPFabric Extender has 2 10-Gigabit Ethernet fabric
interfaces and 24 100/1000BASE-T (100-Mb/1-Gigabit) Ethernet host interfaces.
With this system, you can configure a 1.2 to 1 oversubscription (24 host
interfaces for two fabric interfaces) or higher.

The Cisco Nexus
B22 Fabric Extender for HP (NB22HP) has 8 10-Gigabit Ethernet fabric interfaces
and 16 1G/10-Gigabit Ethernet host interfaces. All host interfaces use all of
the available fabric interfaces. Static pinning and port-channel mode are
supported. When all host interfaces are sending traffic to all fabric
interfaces, the maximum oversubscription ratio for the Cisco Nexus B22 Fabric
Extender for HP (N2K-B22HP-P) is 2:1.

The Cisco Nexus
B22 Fabric Extender for Fujitsu (NB22FTS) has 8 10-Gigabit Ethernet fabric
interfaces and 16 10-Gigabit Ethernet host interfaces. All host interfaces use
all of the available fabric interfaces. Static pinning and port-channel mode
are supported. When all host interfaces are sending traffic to all fabric
interfaces, the maximum oversubscription ratio for the Cisco Nexus B22 Fabric
Extender for Fujitsu (N2K-B22FTS-P) is 2:1.

The Cisco Nexus
B22 Fabric Extender for Dell (NB22DELL) has 8 10-Gigabit Ethernet fabric
interfaces and 16 1G/10-Gigabit Ethernet host interfaces. All host interfaces
use all of the available fabric interfaces. Static pinning and port-channel
mode are supported. When all host interfaces are sending traffic to all fabric
interfaces, the maximum oversubscription ratio for the Cisco Nexus B22 Fabric
Extender for Dell (N2K-B22DELL-P) is 2:1.

The Cisco Nexus
B22 Fabric Extender for IBM (NB22IBM) has 8 10-Gigabit Ethernet fabric
interfaces and 14 1G/10-Gigabit Ethernet host interfaces. All host interfaces
use all of the available fabric interfaces. Static pinning and port-channel
mode are supported. When all host interfaces are sending traffic to all fabric
interfaces, the maximum oversubscription ratio for the Cisco Nexus B22 Fabric
Extender for IBM (N2K-B22IBM-P) is 2:1.

Management
Model

The
Cisco Nexus 2000 Series
Fabric Extender is managed by its parent switch over
the fabric interfaces through a zero-touch configuration model. The switch
discovers the
Fabric Extender by detecting the fabric interfaces of
the
Fabric Extender.

After discovery, if
the
Fabric Extender has been correctly associated with the
parent switch, the following operations are performed:

The switch
checks the software image compatibility and upgrades the
Fabric Extender if necessary.

The switch and
Fabric Extender establish in-band IP connectivity with
each other.

The
switch assigns an IP address in the range of loopback addresses (127.15.1.0/24)
to the
Fabric Extender
to avoid conflicts with IP addresses that might be in use on the network.

The switch
pushes the configuration data to the
Fabric Extender. The
Fabric Extender does not store any configuration
locally.

The
Fabric Extender updates the switch with its
operational status. All
Fabric Extender information is displayed using the
switch commands for monitoring and troubleshooting.

Forwarding Model

The
Cisco Nexus 2000 Series
Fabric Extender
does not perform any local switching. All traffic is sent to the parent switch
that provides central forwarding and policy enforcement, including host-to-host
communications between two systems that are connected to the same
Fabric Extender
as shown in the following figure.

Figure 4. Forwarding Model

The forwarding model facilitates feature consistency between the
Fabric Extender
and its parent Cisco Nexus Series device.

Note

The
Fabric Extender
provides end-host connectivity into the network fabric. As a result, BPDU Guard is enabled on all its host interfaces. If you
connect a bridge or switch to a host interface, that interface is placed in an
error-disabled state when a BPDU is received.

You cannot disable BPDU Guard on the host interfaces of the
Fabric Extender.

The
Fabric Extender
supports egress multicast replication from the network to the host. Packets
that are sent from the parent switch for multicast addresses attached to the
Fabric Extender
are replicated by the
Fabric Extender
ASICs and are then sent to corresponding hosts.

Connection Model

Two methods (the static pinning fabric interface connection and the Port Channel fabric interface connection) allow the traffic from an end host to the parent switch to be distributed when going through the
Cisco Nexus 2000 Series
Fabric Extender.

Note

The Cisco Nexus 2248PQ Fabric Extender does not support the static pinning fabric interface connection.

Static Pinning Fabric Interface Connection

To provide a deterministic relationship between the host interfaces
and the parent switch, you can configure the
Fabric Extender
to use individual fabric interface connections. This configuration connects the
10-Gigabit Ethernet fabric interfaces as shown in the following figure. You can
use any number of fabric interfaces up to the maximum available on the model of
the
Fabric Extender.

Figure 5. Static Pinning Fabric Interface Connections

When the
Fabric Extender
is brought up, its host interfaces are distributed equally among the available
fabric interfaces. As a result, the bandwidth that is dedicated to each end
host toward the parent switch is never changed by the switch but instead is
always specified by you.

Note

If a fabric interface fails, all its associated host interfaces are
brought down and remain down until the fabric interface is restored.

You must use the
pinning max-links command to create a number of
pinned fabric interface connections so that the parent switch can determine a
distribution of host interfaces. The host interfaces are divided by the number
of the max-links and distributed accordingly. The default value is max-links 1.

Caution

Changing the value of the max-links is disruptive; all the host
interfaces on the
Fabric Extender
are brought down and back up as the parent switch reassigns its static pinning.

The pinning order of the host interfaces is initially determined by
the order in which the fabric interfaces were configured. When the parent
switch is restarted, the configured fabric interfaces are pinned to the host
interfaces in an ascending order by the port number of the fabric interface.

To guarantee a deterministic and sticky association across a reboot,
you can manually redistribute the pinning.

Note

The redistribution of the host interfaces will always be in an
ascending order by the port number of the fabric interface.

Port Channel Fabric Interface Connection

To provide load balancing between the host interfaces and the parent
switch, you can configure the
Fabric Extender
to use a port channel fabric interface connection. This connection bundles
10-Gigabit Ethernet fabric interfaces into a single logical channel as shown in
the following figure.

Figure 6. Port Channel Fabric Interface Connection

When you configure the
Fabric Extender
to use a port channel fabric interface connection to its parent switch, the
switch load balances the traffic from the hosts that are connected to the host
interface ports by using the following load-balancing criteria to select the
link:

For a Layer 2 frame, the switch uses the source and destination
MAC addresses.

For a Layer 3 frame, the switch uses the source and destination
MAC addresses and the source and destination IP addresses.

Note

A fabric interface that fails in the port channel does not trigger a
change to the host interfaces. Traffic is automatically redistributed across
the remaining links in the port channel fabric interface.
If all links in the fabric port channel go down, all host interfaces on the FEX are set to the down state.

Port Numbering
Convention

The following port
numbering convention is used for the
Fabric Extender:

interfaceethernetchassis/slot/QSFP-module/port

where

chassis is
configured by the administrator. A
Fabric Extender must be directly connected to its
parent
Cisco Nexus Series device via
individual
fabric interfaces or
a port channel fabric interface. You configure a chassis ID on
a
physical
Ethernet interface or
port channel on the switch to identify the
Fabric Extender that is discovered through those
interfaces.

The chassis ID
ranges from
100
to 199.

Note

The chassis
ID is required only to access a host interface on the
Fabric Extender. A value of less than
100
indicates a slot on the parent switch. The following port numbering convention
is used for the interfaces on the switch:

Fabric Extender Image Management

No software ships with the
Cisco Nexus 2000 Series
Fabric Extender.
The
Fabric Extender
image is bundled into the system image of the parent switch. The image is
automatically verified and updated (if required) during the association process
between the parent switch and the
Fabric Extender.

When you enter the
install all command, it upgrades the software on the parent
Cisco Nexus Series
switch and also upgrades the software on any attached
Fabric Extender.
To minimize downtime as much as possible, the
Fabric Extender
remains online while the installation process loads its new software image.
Once the software image has successfully loaded, the parent switch and the
Fabric Extender
both automatically reboot.

This process is required to maintain version
compatibility between the parent switch and the
Fabric Extender.

Fabric Extender Hardware

Chassis

The
Cisco Nexus 2000 Series Fabric Extender is a 1 RU chassis that is designed for rack mounting. The chassis supports redundant hot-swappable fans and power supplies.

Ethernet
Interfaces

There are 8 models
of the
Cisco Nexus 2000 Series
Fabric Extender:

The
Cisco Nexus 2148T
has 48 1000BASE-T Ethernet host interfaces for its downlink connection to
servers or hosts and 4 10-Gigabit Ethernet fabric interfaces with SFP+
interface adapters for its uplink connection to the parent switch.

The
Cisco Nexus 2224TP
has 24 100BASE-T/1000Base-T Ethernet host interfaces for its downlink
connection to servers or hosts and 2 10-Gigabit Ethernet fabric interfaces with
SFP+ interface adapters for its uplink connection to the parent switch.

The
Cisco Nexus 2248TP
has 48 100BASE-T/1000Base-T Ethernet host interfaces for its downlink
connection to servers or hosts and 4 10-Gigabit Ethernet fabric interfaces with
SFP+ interface adapters for its uplink connection to the parent switch.

The Cisco Nexus
2248TP-E has all the features of the Cisco Nexus 2248TP with these additional
features:

A larger
buffer to absorb large bursts.

Support for
an ingress and egress queue-limit per port.

Support for
debug counters.

Support for
pause no-drop behavior over a cable distance of 3000 meters between the
Fabric Extender
and switch.

Support for
a user configurable shared-buffer.

The Cisco Nexus
B22 Fabric Extender for HP (NB22HP) has 16 1G/10-Gigabit Ethernet host
interfaces. All host interfaces use all of the available fabric interfaces.

The Cisco Nexus
B22 Fabric Extender for Fujitsu (NB22FTS) has 16 10-Gigabit Ethernet host
interfaces. All host interfaces use all of the available fabric interfaces.

The Cisco Nexus
B22 Fabric Extender for Dell (NB22DELL) has 16 1G/10-Gigabit Ethernet host
interfaces. All host interfaces use all of the available fabric interfaces.

The Cisco Nexus
B22 Fabric Extender for IBM (NB22IBM) has 14 1G/10-Gigabit Ethernet host
interfaces. All host interfaces use all of the available fabric interfaces.

Associating a
Fabric Extender to a Fabric Interface

A FEX is connected
to its parent device through
physical
Ethernet interfaces or
a port channel. By default, the parent device does not allow the
attached
Fabric Extender
to connect until it has been assigned a FEX number and is associated with the
connected interface.

Note

The
Fabric Extender
may connect to the switch through a number of separate physical Ethernet
interfaces or one port channel interface.

Note

You must enable the
Fabric Extender
features with the
feature fex
command before you can configure and use a
Fabric Extender
that is connected to the parent switch.

The parent
Cisco Nexus Series
device remembers the type of the
Fabric Extender in its binary
configuration. When this feature is configured, the
Fabric Extender is allowed to come online
only if its type matches the configured FEX type.

Step 6

no type

Example:

switch(config-fex)# no type

(Optional)

Deletes the FEX
type. When a
Fabric Extender is connected to the fabric
interfaces and does not match the configured type that is saved in the binary
configuration on the parent switch, all configurations for all interfaces on
the
Fabric Extender are deleted.

Step 7

pinning max-linksuplinks

Example:

switch(config-fex)# pinning max-links 2

(Optional)

Defines the
number of uplinks. The default is 1. The range is from 1 to 4.

This command is
only applicable if the
Fabric Extender is connected to its parent
switch using one or more statically pinned fabric interfaces. There can only be
one port channel connection.

Caution

Changing the
number of uplinks with the
pinning
max-links command disrupts all the host interface ports of the
Fabric Extender.

Step 8

no pinning max-links

Example:

switch(config-fex)# no pinning max-links

(Optional)

Resets the
number of uplinks to the default.

Caution

Changing
the number of uplinks with the
no pinning
max-links command disrupts all the host interface ports of the
Fabric Extender.

Step 9

serialserial

Example:

switch(config-fex)# serial JAF1339BDSK

(Optional)

Defines a
serial number string. If this command is configured, a switch allows the
corresponding chassis ID to associate (using the
fex associate
command) only if the
Fabric Extender reports a matching serial
number string.

Caution

Configuring
a serial number that does not match the specified
Fabric Extender forces the
Fabric Extender offline.

Step 10

no serial

Example:

switch(config-fex)# no serial

(Optional)

Deletes the
serial number string.

Enabling the Fabric Extender Locator LED

The locator beacon LED on the Fabric Extender allows you to locate a specific Fabric Extender in a rack.

Procedure

Command or Action

Purpose

Step 1

locator-led fexFEX-number

Example:

switch# locator-led fex 101

Turns on the locator beacon LED for a specific Fabric Extender.

Step 2

no locator-led fexFEX-number

Example:

switch# no locator-led fex 101

(Optional)

Turns off the locator beacon LED for a specific Fabric Extender.

Redistributing the Links

When you provision the
Fabric Extender with statically pinned interfaces, the downlink host interfaces on the
Fabric Extender are pinned to the fabric interfaces in the order that they were initially configured. If you want to maintain a specific relationship of host interfaces to fabric interface across reboots, you should repin the links.

You may want to perform this function in these two situations:

A change in the max-links configuration.

If you need to maintain the pinning order of host interfaces to fabric interfaces.

Note

The Cisco Nexus 2248PQ Fabric Extender does not support the static pinning fabric interface connection.

Changing the Number of Links

If you initially configured a specific port on the parent switch, for example port 33, as your only
fabric interface, all 48 host interfaces are pinned to this port. If you
provision another port, for example 35, you must enter the
pinning max-links 2 command to redistribute the host
interfaces. All host interfaces are brought down and host interfaces 1 to 24
are pinned to fabric interface 33 and host interfaces 25 to 48 are pinned to
fabric interface 35.

Maintaining the
Pinning Order

The pinning order of
the host interfaces is initially determined by the order in which the fabric
interfaces were configured. In this example, four fabric interfaces were
configured in the following order:

The next time that
you reboot the
Fabric Extender,
the configured fabric interfaces are pinned to the host interfaces in an
ascending order by port number of the fabric interface. If you want to
configure the same fixed distribution of host interfaces without restarting the
Fabric Extender,
enter the
fex pinning
redistribute command.

Note

It is a misconfiguration to have more fabric ports than pinning
number even if the extra port is in DOWN state.

This example shows how to display the SFP+ transceiver and diagnostic
optical monitoring (DOM) information for
Fabric Extender
uplinks for an SFP+ transceiver that
is plugged into the parent switch interface:

switch# show interface ethernet 1/40 transceiver
Ethernet1/40
sfp is present
name is CISCO-MOLEX INC
part number is 74752-9026
revision is A0
serial number is MOC13321057
nominal bitrate is 12000 MBits/sec
Link length supported for copper is 3 m(s)
cisco id is --
cisco extended id number is 4

This example shows how to display the SFP+ transceiver and DOM information for
Fabric Extender
uplinks for an SFP+ transceiver that
is plugged into the uplink port on the
Fabric Extender:

switch# show interface ethernet 1/40 transceiver fex-fabric
Ethernet1/40
sfp is present
name is CISCO-MOLEX INC
part number is 74752-9026
revision is A0
serial number is MOC13321057
nominal bitrate is 12000 MBits/sec
Link length supported for 50/125mm fiber is 0 m(s)
Link length supported for 62.5/125mm fiber is 0 m(s)
cisco id is --
cisco extended id number is 4

Verifying the
Chassis Management Information

Use the following to
display configuration information used on the switch supervisor to manage the
Fabric Extender.

Command or
Action

Purpose

show diagnostic result fexFEX-number

Displays
results from the diagnostic test for a
Fabric Extender.

show environment fex
{all |
FEX-number} [temperature |
power |
fan]

Displays
the environmental sensor status.

show inventory fexFEX-number

Displays
inventory information for a
Fabric Extender.

show module fexFEX-number

Displays
module information about a
Fabric Extender.

show sprom fexFEX-number {all |
backplane |
powersupplyps-num} |
all

Displays
the contents of the serial PROM (SPROM) on the
Fabric Extender.
The unit of the power for the
show sprom command is displayed in
centi-amperes.

Configuration
Examples for Chassis Management

This example shows
how to display the module information about all connected
Fabric Extender
units:

Configuring the Shared Buffer

The following are guidelines for the configuration of the shared buffer:

Configuring the shared buffer is done at the FEX global level.

The total available buffer is 32 MB which is shared in both the ingress and egress directions.

The default size of the shared buffer is 25392KB.

However, when configuring an Ethernet-based pause no-drop class, the shared buffer size changes to 10800 KB. This change is required to increase the dedicated buffer that supports the pause no-drop class. The pause no-drop class does not use buffer space from the shared-pool.

Note

Performing these commands might result in traffic disruption on all ports.